Surgical method and instrumentation assembly for positioning an ankle prosthesis

ABSTRACT

This surgical ankle repair method comprises the steps of providing an instrumentation assembly for positioning an ankle prosthesis, the instrumentation assembly including a talar alignment instrument and a cutting block, the talar alignment instrument comprising a front portion and two fins extending from the ends of the front portion, said fins being adapted to be positioned in gutters extending below a tibia of a patient and around a trochlea of a talus of the patient, each fin including a reference marker, the cutting block comprising a tibial alignment structure and a recess which engages a protrusion provided on the talar alignment instrument, positioning the talar alignment instrument such that the fins are disposed in the gutters extending below the tibia and around the trochlea of the talus; aligning the talar alignment instrument so that the fins are parallel to the rotational plane of the talus, perpendicular to the rotational axis of the talus, and so that the reference markers are aligned with a longitudinal axis of the tibia; confirming alignment of the reference markers via imaging technology; mechanically attaching the talar alignment instrument to the talus; fastening the cutting block to the talar alignment instrument such that the recess engages the protrusion locked in a parallel orientation to the rotational plane of the talus; rotating the talus such that the tibial alignment structure is in a parallel alignment to the longitudinal axis of the tibia, thereby correcting any varus or valgus deformity of the talus; attaching the tibial alignment structure to the tibia; and performing a first resection of the talus and at least one resection of the tibia using the cutting block.

The present application claims priority to U.S. Provisional ApplicationNo. 62/129,593 filed Mar. 6, 2015 incorporated herein by reference.

The present invention concerns a surgical ankle repair method. Thepresent invention also concerns a surgical instrumentation assembly forpositioning an ankle prosthesis.

The ankle implants are generally positioned using the tibia as areference, as disclosed in US-A-2013/0116797. A cutting block isattached to the tibia and aligned with the axis of the tibia, andresections of the talus are performed after having found the right footposition with respect to at least one rotational plane of the ankle.

The positioning of the resections of the talus may be challenging as therotational plane of the talus is found by techniques whose accuracy canbe improved. Inaccuracies in the positioning of the implants can resultin excessive stresses on the bones and soft tissues around the implants,and may reduce longevity of the implants.

The aim of the invention is to provide a new surgical method whichpermits the physician to better position the prostheses with respect tothe bones of the patient.

To this end, the invention concerns a surgical ankle repair methodcomprising the steps of:

-   -   a) providing an instrumentation assembly for positioning an        ankle prosthesis, the instrumentation assembly including a talar        alignment instrument and a cutting block, the talar alignment        instrument comprising a front portion and two fins extending        from the ends of the front portion, said fins being adapted to        be positioned in gutters extending below a tibia of a patient        and around the trochlea of a talus of the patient, each fin        including a reference marker, the cutting block comprising a        tibial alignment structure and a recess which engages a        protrusion provided on the talar alignment instrument,    -   b) positioning the talar alignment instrument such that the fins        are disposed in the gutters extending below the tibia and around        the trochlea of the talus;    -   c) aligning the talar alignment instrument so that the fins are        parallel to the rotational plane of the talus, perpendicular to        the rotational axis of the talus, and so that the reference        markers are aligned with a longitudinal axis of the tibia;    -   d) confirming alignment of the reference markers via imaging        technology;    -   e) mechanically attaching the talar alignment instrument to the        talus;    -   f) fastening the cutting block to the talar alignment instrument        such that the recess engages the protrusion locked in a parallel        orientation to the rotational plane of the talus;    -   g) rotating the talus such that the tibial alignment structure        is in a parallel alignment to the longitudinal axis of the        tibia, thereby correcting any varus or valgus deformity of the        talus;    -   h) attaching the tibial alignment structure to the tibia; and    -   i) performing a first resection of the talus and several        resections of the tibia using the cutting block.

Thanks to the invention, the resections of the tibia and the talus areperformed using the talus as reference, resulting in better alignmentand positioning of the implants.

According to further aspects of the invention which are advantageous butnot compulsory, such a surgical method may incorporate one or several ofthe following features:

-   -   The imaging technology is selected from the group consisting of        X-ray, CT, and MR imaging.    -   The method comprises, after step i), a further step j)        consisting in inserting, in at least one hole drilled in the        talus at step e) for inserting screws adapted to mechanically        attach the talar alignment instrument to the talus, a        positioning element for positioning a cutting guide for        performing a second resection of the talus.    -   The at least one resection performed on the talus at step i) is        a posterior chamfer, whereas at step j) the cutting guide for        performing the second resection is also positioned against the        posterior chamfer.    -   The method comprises, after step j), a further step k)        consisting in positioning, on the surface of the second        resection, a cutting guide for performing a third resection of        the talus, which forms with the second resection an anterior        chamfer.    -   The talar alignment instrument is used to align a second cutting        guide for performing a second resection of the talus.    -   The second cutting guide remains on the talus surface, the talar        alignment instrument is removed and a third cutting guide is        placed on the second cutting guide to perform a third resection        of the talus which forms with the second resection an anterior        chamfer.    -   At least one hole drilled in the talus at step e) for inserting        screws adapted to mechanically attach the talar alignment        instrument to the talus is used for drilling a hole destined to        receive an anchoring peg of a talus implant.    -   The talar alignment instrument is mechanically attached to the        talus using at least two screws.    -   The reference markers for the fins mark a direction        perpendicular of the fins.        The invention also concerns a surgical ankle replacement method        comprising the steps of:    -   a) placing a talar alignment instrument on the talus,    -   b) positioning the talar alignment instrument on the talus    -   c) aligning a reference marker provided on the talar alignment        instrument    -   d) mechanically attaching the talar alignment instrument to the        talus,    -   e) fastening a cutting block to the talar alignment instrument,    -   f) locking a relative position of the cutting block and the        tibia,    -   g) performing, using the cutting block, at least one resection        of a lower surface of the tibia and at least one resection of a        top surface of the talus.

According to further aspects of the invention which are advantageous butnot compulsory, such a surgical replacement method may incorporate oneor both of the following features:

-   -   At step b) the talon alignment instrument is positioned relative        to a rational plane of the talus and to a rational axis of the        talus.    -   At step c) the reference marker allows matching of the        instrument's axis and radii to the talus's radii and axis.

The invention also concerns a surgical instrumentation assembly forpositioning an ankle prosthesis, the ankle prosthesis including a tibiaimplant and a talus implant, wherein the instrumentation assemblycomprises:

-   -   a talar alignment instrument adapted to be placed on a talus of        a patient, and relative to the rotational plane of the talus,        and centered on the rotational axis of the talus, and        perpendicular to the rotational plane of the talus and        mechanically attached to the talus,    -   a cutting block adapted to be fastened to the talar alignment        instrument and locked with respect to the tibia.

According to further aspects of the invention which are advantageous butnot compulsory, such a surgical instrumentation assembly may incorporateone or several of the following features:

-   -   The talar alignment instrument comprises a front portion and two        fins extending from the ends of the front portion, said fins        being adapted to be positioned in gutters extending below the        tibia and around the trochlea of the talus.    -   The front portion comprises holes for inserting screws for        mechanically attaching the talar alignment instrument to the        talus.    -   The front portion comprises a protruding portion adapted to be        received in a recess of the cutting block, the recess and the        protruding portion being configured to prevent relative        displacement of the talar alignment instrument and the cutting        block, and locking parallel to the rotational plane of the        talus.    -   The recess and the protruding portion are complementary shaped.    -   The fins of the talar alignment instrument are provided with        reference markers adapted to mark a direction perpendicular to        the fins, and adapted to be aligned with the longitudinal axis        of the tibia, and aligned to the rotational axis of the talus.    -   The reference markers are elongated slots.    -   The cutting block comprises a tibial alignment structure adapted        to be aligned with the longitudinal axis of the tibia and        mechanically attached to the tibia.    -   The cutting block is configured to permit the cutting of at        least one surface or hole on the top surface of the talus and        cutting of at least one surface or hole in the distal portion of        the tibia.    -   The assembly further comprises one or several cutting guides        configured to permit the cutting of additional surfaces or holes        on the top surface of the talus, whereas said cutting guides are        adapted to be positioned against prior cut surfaces or holes.    -   At least one of the cutting guides for cutting additional        surfaces or holes comprises at least one positioning shape        adapted to be positioned against a screw inserted in a hole        previously drilled in the talus for inserting a screw for        mechanically attaching the talar alignment instrument to the        talus.    -   At least one of the cutting guides for the cutting additional        surfaces comprises of at least one positioning shape adapted to        be positioned against the talar alignment instrument attached to        the talus.

The invention will now be explained in reference to the followingfigures, as an illustrative example. In the annexed figures:

FIG. 1 is a perspective view of a talar alignment instrument belongingto an instrumentation assembly according to the invention;

FIG. 2 is a perspective view of the positioning of the talar alignmentinstrument of FIG. 1 on a talus;

FIG. 3 is a side view of the positioning of the talar alignmentinstrument of FIG. 1 with respect to the talus and the tibia of apatient;

FIG. 4 is a front view of the positioning of the talar alignmentinstrument of FIG. 1 on a talus;

FIG. 5 is a perspective view of a cutting block belonging to aninstrumentation assembly according to the invention and a talaralignment instrument positioned on a talus;

FIG. 6 is a front view of the cutting block of FIG. 5 positioned withrespect to a talus and a tibia;

FIG. 7 is a side view of the talar alignment instrument and the cuttingblock during cutting of resections of the tibia and the talus;

FIG. 8 is a perspective view of an ankle after resections have beenperformed;

FIGS. 9 and 10 are perspective views similar to FIG. 8, during resectionof other portions of the talus;

FIG. 11 is a front view of an ankle articulation equipped with tibia andtalus implants shown in ghost lines;

FIG. 12 is a side view of the ankle articulation, tibia and talusimplants of FIG. 11;

FIG. 13 is a view similar to FIG. 11 showing only the tibial implant.

A surgical method and an instrumentation assembly are described belowfor replacing an ankle articulation on a patient, by implanting tibiaand talus prostheses. The method and the instruments described below canbe used for implanting ankle prostheses having a wide variety ofstructures, for example having tibia and/or talus implants that areconstituted by a plurality of parts assembled to one another, and thatmay be made of metal, polymer, ceramic, composite, and a variety ofother materials.

For convenience, the description below describes directions relative tothe bones of an ankle in their anatomical position, the terms posterioror rear, anterior, front, right, left, upper, lower, etc. should beunderstood relative to the ankle of a patient standing on asubstantially horizontal surface and viewed from the ankle.

Initially, the bones of the ankle of the patient which include a talus Tand a tibia B, need to be prepared by performing resections forreceiving the implants.

The instrumentation assembly comprises a talar alignment instrument 2represented in FIG. 1. This talar alignment instrument 2 is adapted tobe placed on the talus T during a first step of the surgical methodaccording to the invention. The talus alignment instrument 2 comprises afront portion 20 and two fins 22 and 24 extending from the lateral mostportions or ends 22 a of front portion 20 in a substantiallyperpendicular direction. In the example, the fins 22 and 24 areindependent parts which are fixed to the front portion 20, for example,by screws 26. Advantageously, the fins 22 and 24 may be made of anelastic metal, such as nitinol, so as to provide a flexibility suitablefor adaptation of the talar alignment instrument to various ankleanatomies.

The resections performed on the talus T and the tibia B are performedusing as a reference the talar alignment instrument 2, which is fixed tothe talus T and positioned with respect to the rotational plane P1, andthe talus T. The rotational plane P1 is best defined by the interfacebetween the tibia, fibula, and talus. Since the tibia and fibular sharethis interface, the talus is the singular bone that best defines thissurface. This part of the talus is called the trochlea, and where thetalar alignment instrument directly attaches. This permits to providebetter accuracy for the positioning of the implants and therefore toobtain a better comfort for the patient and a longer longevity of theimplants.

The use of the talus T as reference for the bone resections also permitsto determine the size of the implants. The trochlea of the talus asdescribed above, also defines the width of the implant. Since the talaralignment instrument attaches directly to the trochlea, the width isdetermined accurately and therefore the size of the implant isaccurately selected.

According to a non-shown embodiment, the talar alignment instrument 2may be a monolithic or unitary structure, with the fins 22 and 24 andfront portion 20 comprising 1 piece.

The fins 22 and 24 are adapted to be positioned in gutters G1 and G2 oftalus T which extend around a trochlea T1 of the talus T, which is aglobally cylindrical portion of the talus T. The gutters G1 and G2extend below a portion of a tibia B and a portion of a fibula F. Thegutter G1 is the vertical joint spaces comprised of the lateral side ofthe trochlea and inner side of the fibula. The gutter G2 is the verticaljoint space comprised of the medial side of the trochlea and inner sideof tibia's medial malleolus. The tibia B, the fibula F and the talus Ttogether form the ankle articulation of a patient.

A second step of the surgical method consists in positioning the talusalignment instrument 2 so that the fins 22 and 24 are substantiallyparallel to a rotational plane P1 of the talus T. The rotational planeP1 is the plane defined by the rotation of the talus T with respect tothe tibia B around a rotational axis X1 which is substantially parallelto a horizontal surface on which the patient is virtually standing, andwhich extends along a right-left direction of the ankle. The fins 22 and24 have a substantially planar shape perpendicular to rotational axisX1. The fins 22 and 24 are also positioned in alignment of rotationalaxis X1.

A further step of the surgical method, which is represented on FIG. 3,consists in aligning reference markers provided on the talar alignmentinstrument 2 with a longitudinal axis XB (illustrated in FIG. 6) of thetibia B. In the example shown, the reference markers are elongatedslots, which may be holes 220 and 240 which are provided on fins 22 and24 and adapted to mark a direction perpendicular to a longitudinal axisX22 of the fins 22 and 24. The alignment of the reference markers 220and 240 is checked by imaging using for example X-rays, magneticresonance imaging (MRI) or computed tomography (CT).

According to a non-shown embodiment, the reference markers may be othergeometrically shaped holes allowing visualization and alignmentutilizing, for example, X-rays, CT or MRI of the fins 22 and 24 toobtain perpendicular images to the talar alignment instrument 2.Alternatively, the reference markers may also be protrusions or recessesadapted to be visible in the above-mentioned imaging techniques.

The talar alignment instrument 2 is then mechanically attached to thetalus T, using at least two screws 3 represented on FIGS. 8 and 9. Thescrews 3 are inserted through holes 30 provided in the front portion 20and in the holes drilled in the talus T.

During the positioning and attachment steps of the talar alignmentinstrument 2, the instrument 2 is handled or connected to a rod 4 havingan end adapted to be inserted in a protruding portion 32 of frontportion 20. The protruding portion 32 comprises an inner recess 320having a hexagonal shape complementary with the distal end of the rod 4,which prevents rotation of the instrument 2 around the longitudinal axisof the rod 4.

According to a non-shown embodiment of the invention, instead of havinga hexagonal shape, the inner recess 320 may present any other differentshape adapted to prevent relative rotation between the rod 4 and thetalar alignment instrument 2, for example a square shape, an ovoidshape, etc.

The instrumentation assembly also includes a cutting block 5,represented on FIG. 5. The cutting block 5 comprises slots 50 forpassing cutting instruments which perform resections of a top surface T2of the talus T and a lower surface B1 of the tibia B, as it will bedescribed later.

The slots 50 are provided on a lower portion 55 of the cutting block 5.This lower portion 55 also includes a recess 54 adapted to receive theprotruding portion 32 of the talar alignment instrument 2. The recess 54and the protruding portion 32 are therefore complementary shaped inorder to prevent relative rotation between the cutting block 5 and thetalar alignment instrument 2. In the example, recess 54 and protrudingportion 32 have a parallelepiped shape. In a non-shown embodiment, theshape of recess 54 and protruding portion 32 may be of any other shapeadapted to prevent relative rotation.

The cutting block 5 also includes a tibial alignment structure 56 whichextends substantially vertically from an upper portion 52 of the cuttingblock 5. The tibial alignment structure 56 is terminated by an upperalignment device 560.

In a further step, the cutting block 5 is attached to the talaralignment instrument 2 by mounting the recess 54 on the protrudingportion 32 and by inserting a screw 7 through the recess 54 and in athreaded bore 322 provided in protruding portion 32.

Once the cutting block 5 is fastened to the talar alignment instrument2, the talus T is rotated with respect to the tibia B by moving the footof the patient so that the tibial alignment structure 56 is in parallelalignment to the longitudinal axis XB of the tibia B, as shown on FIG.6. In this step, the talus T is rotated in a plane perpendicular to therotational plane P1 and comprising the longitudinal axis XB. By aligningthe tibial alignment structure 56 with the longitudinal axis XB, varusor valgus deformities of the talus T are corrected.

Following the varus or valgus deformities correction, the cutting block5 and the tibia B are mechanically attached so that the relativeposition of the talus T and the tibia B is locked in the subsequentsteps of the surgical method. Several holes are drilled in the tibia Busing drilling guides 58 provided on the lower portion 55 and on thetibial alignment structure 56. Pins 8 are inserted into the drillingguides 58 and in the holes drilled in the tibia B, as shown on FIG. 7,so that the cutting block 5 cannot move with respect to the tibia B. Thealignment device 560 is also attached to a non-shown upper portion ofthe tibia B using non-shown attaching means.

Once the cutting block 5 is fixed with respect to the talus T and thetibia B, resections of the talus T and the tibia B can be performed soas to prepare the bones of the patient for the mounting of the anklereplacement implants. A top portion of the talus T is resected bycutting a posterior chamfer 10 represented on FIG. 8. This resection isperformed using a saw blade 11 inserted in an angled slot of lowerportion 55.

As represented on FIG. 8, resections of the lower surface B1 of thetibia B are performed by non-shown cutting blades, so as to form asquare-shaped lodgment B2 comprising flat surfaces adapted to receive atibial implant. A cylindrical recess 13 is drilled in the tibia B usinga drill bit 15 inserted into a drilling guide 60 of cutting block 5. Therecess 13 is destined to receive an anchoring keel of a tibial implant.A vertical hole 13B is also cut for linking the cylindrical recess 13 tothe outer resected surface of the lodgment B2. The cutting block 5 isthen removed. It should be noted that no additional holes are requiredto attach the cutting block to the talus, which may be referred to as“bonus holes”. In reducing the number of holes created in the bone, boneloss is minimized.

In a further step of the surgical method, an anterior chamfer 17 isresected on the top surface of the talus T. This anterior chamfer 17,which is visible on FIG. 12, is obtained in two consecutive operations,shown in FIGS. 9 and 10.

In FIG. 9, a second cutting guide 19 of the instrumentation assembly,comprising a backwards extending portion 190 having a planar lowersurface, is positioned against the posterior chamfer 10. The secondcutting guide 19 also includes a front portion 192 which comprises aplate 192 a adapted to be positioned against protruding portion 32thanks to non-shown complementary shaped surfaces. The front portion 192is extended by a rod 194 for handling the cutting guide 19.

As an optional feature, the second cutting guide 19 comprises twolodgments 196 which define cylindrical slots for passing two pins 21,which are inserted in non-shown holes drilled in the talus T. The pins21 permit to further lock the position of the second cutting guide 19with respect to the talus T.

The second cutting guide 19 comprises several cylindrically shapedlodgments 198 adapted to receive a drilling bit 23 used to cut a firstportion 17 a, visible on FIG. 10 of the anterior chamfer 17. As shown onFIG. 9, the first portion 17 a of the anterior chamfer 17 is obtained byfive adjacent consecutive drilling operations. As an alternative, thefirst portion 17 a of the anterior chamfer 17 may be obtained usingdifferent drilling or cutting means.

On FIG. 10, a second portion 17 b of the anterior chamfer 17 isresected. During this operation, the second cutting guide 19 is keptinto place, the talar alignment instrument 2 is dismounted, leaving opena hole 100 of the talus T, in which one of the screws 3 was present toattach the talar alignment instrument 2 to the talus T. The frontportion 192 of the second cutting guide 19 is removable from a mainportion of the second cutting guide 19, which comprises the lodgments198. This front portion 192 is removed and replaced by a third cuttingguide 9 of the instrumentation assembly. The third cutting guide 9comprises five adjacent lodgments 90 adapted to receive a drilling bit25, which could be the same as drilling bit 23, and which is adapted todrill the second portion 17 b of the entire chamfer 17 in five drillingoperations. The third cutting guide 9 also comprises, extending besideslodgments 90, a positioning block 92 adapted to be inserted in thelodgments 198 of the second cutting guide 19 to lock in position thethird cutting guide 9 with respect to the second cutting guide 19. Thepositioning block 92 is inserted in the second cutting guide 19, a lowerend of the positioning block 92 is in contact with the first portion 17a of the anterior chamfer 17.

When the second portion 17 b is obtained, the resection of the anteriorchamfer 17 is complete and a talus implant 16 can be mounted on thetalus T, as shown on FIGS. 11 and 12. The talus implant 16 comprises anarticulation surface 160, and two anchoring pegs 162, which are insertedin the holes 100 in which the screws 3 for fixing the talar alignmentinstrument 2 were inserted. The holes 100 may be prepared for thereception of the pegs 162 by a drilling at the diameter of the pegs 162.

A tibia implant 18 is inserted in the recess 13 prepared in the tibia B.Suitable tibia implants include, for example, Salto Talaris™ Total AnkleProsthesis (manufactured by Tornier), INFINITY® total ankle system(manufactured by INBONE), Scandinavian Total Ankle Replacement (STAR™Ankle) (manufactured by Stryker), Integra® Total Ankle Prosthesis(manufactured by Integra), Zenith™ Total Ankle Replacement (manufacturedby Corin), BOX® Total Ankle Replacement (manufactured by MatOrtho®).

The holes 100 which are drilled for receiving screws 3 for attachingtalus alignment instrument 2 to the talus T are used to receiveanchoring pegs 162 of the talus implant 16. This permits the physicianto reduce the number of holes drilled in the bones during the surgicalprocedure and which are left unused after the ankle replacement.

According to a non-shown embodiment of the invention, after the cuttingof the posterior chamfer 10, the talar alignment instrument 2 may beremoved. In such a case, the holes 30 of the front portion 20 may beprovided with a lateral getaway formed by a slot so that the talaralignment instrument 2 can be removed without dismounting the screws 3,which are left inserted in the talus T.

To cut the first portion 17 a of the anterior chamfer 17, a cuttingguide similar to the cutting guide 19 is positioned against the screws 3and against the posterior chamfer 10.

Once the first portion 17 a is drilled, the cutting guide is removed anda second cutting guide is positioned against the posterior chamfer 10and the first portion 17 a of the anterior chamfer 17. The secondportion 17 b of the anterior chamfer 17 is then drilled.

Other embodiments are envisioned and within the scope of thisapplication including patient specific instruments and implants. Ankleprosthesis instruments including tibial and talar guides may be preparedor manufactured based on patient specific anatomical data obtained usingimaging technology including but not limited to X-ray, CT, and MRIimaging. In one embodiment, a physician may use anatomical imaging dataof a patient and transmit this anatomical data to an instrument/implantmanufacturer, wherein the instrument/implant manufacturer can create aninstrument and/or implant which is designed based on the patient'sspecific anatomical data. Talar alignment instruments, cutting guides,cutting blocks, screws, and jigs may be manufactured with surfaces,angles, orientations, and structures which conform or complement thespecific anatomy of the patient. For example, cutting guides havingslots and (pin) holes for cutting the talus and aligning the ankle mayinclude geometries conforming to anatomical surfaces or regions of thetibia, talus, other anatomical ankle bones, tendons, muscles, andmarkers.

In one particular embodiment, the talar alignment instrument 2 of thepresent disclosure may be created using patient specific anatomicaldata. More specifically, images of a patient may be obtained using MRI,X-ray, CT and combinations thereof. Images/scans may be represented as avirtual model of the patient's anatomy whereupon a physician may createand size patient specific implants and instruments. Alternatively imagesand/or scans of a patient's anatomy may be sent to an implant/instrumentmanufacturer whereupon a custom designed, or patient specificimplant/instrument may be created. Specifically, scans of the hard andsoft tissues can be used to create custom instrumentation, tools andimplants for total ankle prostheses, including, but not limited to,talar alignment instruments, and cutting blocks and jigs having cuttingslots and drill guides which are specific to the patient'sanatomy/geometry. With regards to the current invention, the talaralignment instrument may include fins corresponding to patient anatomyincluding the gutters on the trochlea and taking into account any varusand valgus deformities.

In another embodiment, patient specific instruments/implants can becreated by first taking into account a patient's corrected anatomy andthen building the implants, instruments and tools to correspond to thecorrected anatomy. In more detail, a surgeon can use patient anatomicalimages, such as x-ray and CT images and load those images into 3-D CADsoftware and correct a varus or valgus deformity first in a 3-Dsoftware, next a patient specific cutting jig or block is generatedbased on the corrected deformity. Once the block is manufactured, thesurgeon may secure the patient specific block when the ankle is plantarflexed, enabling the surgeon to attach the patient specific cuttingblock to the talus only. The surgeon can correct the varus or valgusdeformity by rotating the cutting block left and right, or medially andlaterally. Next, the surgeon may then align the cutting block with thelongitudinal axis of the tibia and place a pin in the tibia to attachthe patient specific cutting block to the tibia. It should be noted thatthe aforementioned surgical steps are all performed while the ankle isplantar flexed, exposing maximum surface area of the talus to accuratelyposition and attach the talus. The invention also concerns a kit forpositioning an ankle prosthesis including a talar alignment instrumentand a cutting block, the talar alignment instrument comprising a frontportion and two fins extending from the ends of the front portion, saidfins being adapted to be positioned in gutters extending below a tibiaof a patient and around the trochlea of a talus of the patient, each finincluding a reference marker of a direction perpendicular to the fins,the cutting block comprising a tibial alignment structure and a recesswhich engages a protrusion provided on the talar alignment instrument.

The invention also concerns a surgical ankle repair method comprising,before the step of providing an instrumentation assembly, a first stepconsisting in performing MRI, CT or X-ray imaging of the anatomy of apatient, and wherein the step of providing an instrumentation assemblyis realized on the basis of the anatomical data of the patient providedby said imaging. More specifically, the imaging data may be used todesign a talar alignment instrument adapted to be placed on a talus of apatient, and relative to the rotational plane of the talus, and centeredon the rotational axis of the talus, and perpendicular to the rotationalplane of the talus and mechanically attached to the talus, and a cuttingblock adapted to be fastened to the talar alignment instrument andlocked with respect to the tibia.

In certain embodiments, the imaging data collected can be used by thesurgeon in planning procedural steps, including, but not limited to,planning surgical cuts or bone and tissue resection.

The technical features of the above-described embodiment and variantscan be combined to form new embodiments of the invention.

1. A surgical ankle repair method comprising the steps of: a) providingan instrumentation assembly for positioning an ankle prosthesis, theinstrumentation assembly including a talar alignment instrument and acutting block, the talar alignment instrument comprising a front portionand two fins extending from the ends of the front portion, said finsbeing adapted to be positioned in gutters extending below a tibia of apatient and around a trochlea of a talus of the patient, each finincluding a reference marker, the cutting block comprising a tibialalignment structure and a recess which engages a protrusion provided onthe talar alignment instrument, b) positioning the talar alignmentinstrument such that the fins are disposed in the gutters extendingbelow the tibia and around the trochlea of the talus; c) aligning thetalar alignment instrument so that the fins are parallel to therotational plane of the talus, perpendicular to the rotational axis ofthe talus, and so that the reference markers are aligned with alongitudinal axis of the tibia; d) confirming alignment of the referencemarkers via imaging technology; e) mechanically attaching the talaralignment instrument to the talus; f) fastening the cutting block to thetalar alignment instrument such that the recess engages the protrusionlocked in a parallel orientation to the rotational plane of the talus;g) rotating the talus such that the tibial alignment structure is in aparallel alignment to the longitudinal axis of the tibia, therebycorrecting any varus or valgus deformity of the talus; h) attaching thetibial alignment structure to the tibia; and i) performing a firstresection of the talus and at least one resection of the tibia using thecutting block.
 2. The surgical method of claim 1, wherein the imagingtechnology is selected from the group consisting of X-ray, CT, and MRimaging.
 3. The surgical method of claim 1, wherein the methodcomprises, after step i), a further step j) consisting in inserting, inat least one hole drilled in the talus at step e) for inserting screwsadapted to mechanically attach the talar alignment instrument to thetalus, a positioning element for positioning a cutting guide forperforming a second resection of the talus.
 4. The surgical method ofclaim 3, wherein the at least one resection performed on the talus atstep i) is a posterior chamfer, and wherein at step j) the cutting guidefor performing the second resection is also positioned against theposterior chamfer.
 5. The surgical method of claim 4, wherein the methodcomprises, after step j), a further step k) consisting in positioning,on the surface of the second resection, a cutting guide for performing athird resection of the talus, which forms with the second resection ananterior chamfer.
 6. The surgical method of claim 1, wherein the talaralignment instrument is used to align a second cutting guide forperforming a second resection of the talus.
 7. The surgical method ofclaim 6, wherein the second cutting guide remains on the talus surface,the talar alignment instrument is removed and a third cutting guide isplaced on the second cutting guide to perform a third resection of thetalus which forms with the second resection an anterior chamfer.
 8. Thesurgical method of claim 1, wherein at least one hole drilled in thetalus at step e) for inserting screws adapted to mechanically attach thetalar alignment instrument to the talus is used for drilling a holedestined to receive an anchoring peg of a talus implant.
 9. The surgicalmethod of claim 1, wherein the talar alignment instrument ismechanically attached to the talus using at least two screws.
 10. Thesurgical method of claim 1, wherein the reference markers of the finsmark a direction perpendicular to the fins.
 11. A surgical anklereplacement method comprising the steps of: a) placing a talar alignmentinstrument on the talus, b) positioning the talar alignment instrumenton the talus, c) aligning a reference marker provided on the talaralignment instrument, d) mechanically attaching the talar alignmentinstrument to the talus, e) fastening a cutting block to the talaralignment instrument, f) locking a relative position of the cuttingblock and the tibia, g) performing, using the cutting block, at leastone resection of a lower surface of the tibia and at least one resectionof a top surface of the talus.
 12. The surgical ankle replacement methodof claim 11, wherein at step b) the talar alignment instrument ispositioned relative to a rotational plane of the talus and to arotational axis of the talus.
 13. The surgical ankle replacement methodof claim 11, wherein at step c) the reference marker allows matching ofthe instrument's axis and radii to the talus's radii and axis.
 14. Asurgical instrumentation assembly for positioning an ankle prosthesis,the ankle prosthesis including a tibia implant and a talus implant,wherein the instrumentation assembly comprises: a talar alignmentinstrument adapted to be placed on a talus of a patient, and relative tothe rotational plane of the talus, and centered on the rotational axisof the talus, and perpendicular to the rotational plane of the talus andmechanically attached to the talus, a cutting block adapted to befastened to the talar alignment instrument and locked with respect to atibia of the patient.
 15. The surgical instrumentation assembly of claim14, wherein the talar alignment instrument comprises a front portion andtwo fins extending from the ends of the front portion, said fins beingadapted to be positioned in gutters extending below the tibia and arounda trochlea of the talus.
 16. The surgical instrumentation assembly ofclaim 15, wherein the front portion comprises holes for inserting screwsfor mechanically attaching the talar alignment instrument to the talus.17. The surgical instrumentation assembly of claim 15, wherein the frontportion comprises a protruding portion adapted to be received in arecess of the cutting block, the recess and the protruding portion beingconfigured to prevent relative displacement of the talar alignmentinstrument and the cutting block, and locking parallel to the rotationalplane of the talus.
 18. The surgical instrumentation assembly of claim17, wherein the recess and the protruding portion are complementaryshaped.
 19. The surgical instrumentation assembly of claim 15, whereinthe fins of the talar alignment instrument are provided with referencemarkers adapted to mark a direction perpendicular to the fins, andadapted to be aligned with the longitudinal axis of the tibia, andaligned to the rotational axis of the talus.
 20. The surgicalinstrumentation assembly of claim 19, wherein the reference markers areelongated slots.
 21. The surgical instrumentation assembly of claim 14,wherein the cutting block comprises a tibial alignment structure adaptedto be aligned with the longitudinal axis of the tibia and mechanicallyattached to the tibia.
 22. The surgical instrumentation assembly ofclaim 14, wherein the cutting block is configured to permit the cuttingof at least one surface or hole on the top surface of the talus andcutting of at least one surface or hole in the distal portion of thetibia.
 23. The surgical instrumentation assembly of claim 22, whereinthe assembly further comprises one or several cutting guides configuredto permit the cutting of additional surfaces or holes on the top surfaceof the talus, and wherein said cutting guides are adapted to bepositioned against prior cut surfaces or holes.
 24. The surgicalinstrumentation assembly of claim 23, wherein at least one of thecutting guides for cutting additional surfaces or holes comprises atleast one positioning shape adapted to be positioned against a screwinserted in a hole previously drilled in the talus for inserting a screwfor mechanically attaching the talar alignment instrument to the talus.25. The surgical instrumentation assembly of claim 23, wherein at leastone of the cutting guides for the cutting additional surfaces comprisesof at least one positioning shape adapted to be positioned against thetalar alignment instrument attached to the talus.